Catheters are placed at various locations within a patient for a wide variety of purposes and medical procedures. For example, one type of catheter is a balloon dilatation catheter which is used in the treatment of a vascular stenosis. Such a catheter has a balloon at its distal end which is intended to be placed, in a deflated condition, within the stenosis, and then inflated while in the stenosis to expand radially the stenosis lumen of the blood vessel. The prior art includes essentially three types of balloon dilatation catheters: "Over-the-wire" catheters, "monorail" catheters and "fixed balloon on a wire" catheters. A fourth type of balloon dilatation catheter, "telescoping" catheters, is the subject of co-pending application Ser. No. 08/198,628 filed Feb. 18, 1994. A telescoping catheter comprises a plurality of telescoping tubes arranged so that the effective "over-the-wire length" of the telescoping catheter can be adjusted.
Typically, the placement of a telescoping catheter involves inserting a guiding catheter into the patient's vasculature. A connector, such as a Tuohy-Borst connector, is disposed at the proximal end of the guiding catheter extending outside of the patient. The connector is opened and a guidewire is advanced through the guiding catheter and the patient's vasculature to the location of the stenosis to be treated. The telescoping catheter, which has a guidewire lumen adapted to receive the guidewire, then is advanced over the guidewire to the stenosis, or, alternatively, the wire and telescoping catheter may be advanced in unison to the stenosis with the guidewire protruding from the distal end of the telescoping catheter.
The telescoping catheter requires the Tuohy-Borst connector to remain open while the catheter and/or guidewire is maneuvered to and from the stenosis. The structure of the telescoping catheter minimizes the amount of backbleeding from the patient's vasculature. Consequently, there is no need for an anti-backbleed device to be disposed at the proximal end of the telescoping catheter. The hub disposed at the proximal end of the telescoping catheter may be a standard hub which is well known in the art.
In the telescoping catheter, the hub is affixed to the proximal end of the proximal telescoping tube. This hub has a central port through which the inflation shaft and the guidewire can be passed. However, the known telescoping catheters do not include a hub that can be used to lock the inflation shaft or the guidewire in a fixed position relative to the hub.
In the performance of a catheterization procedure, it may become necessary to exchange an indwelling telescoping catheter for another catheter having a different sized balloon. With the known telescoping catheters, in order to maintain the guidewire in position across the stenosis, the user must manually grip the guidewire with his fingers at a location just proximal of the hub to prevent the guidewire from being pulled out of the blood vessel with the catheter. In so doing, the user is left with just one free hand with which to remove the indwelling telescoping catheter from the patient.
Furthermore, when the telescoping catheter is loaded onto or removed from the guidewire, it is preferable to maintain the telescoping tubes in the fully retracted position. In the known telescoping catheters, this is accomplished by fully retracting the telescoping tubes and then gripping the inflation tube just proximal of the hub. In so doing, the user is left with just one free hand with which to load the telescoping catheter on to the guidewire and to remove the telescoping catheter from the guidewire.
There is, therefore, a need for a new and improved hub that will allow the guidewire or inflation shaft to be locked in a fixed position-relative to the hub.
In general, it is an object of the present invention to provide a hub for use in a telescoping catheter that is adapted to lock the guidewire or inflation shaft in a fixed position relative to the hub. However, the present invention is not limited to telescoping catheters. The present invention may be readily adapted to be used with other catheter assemblies such as over-the-wire, monorail, and fixed wire catheters.